At present, the plasma technique is used extensively in many industries including petrochemical, optoelectronic and semiconductor industry, 3C and automobile parts industry, livelihood and food industry, and biomedical material industry, etc, and most of the well-developed plasma techniques are applied in a vacuum process with many drawbacks, such as a long vacuum time, a high cost for the vacuum equipments and related maintenance fees, an object size limited by the size of the cavity, and unable to perform continuous processes on a production line. Although the most economical and efficient method of producing plasma is working under atmospheric pressure, for maintaining the stability of the plasma, the system is generally operated at a low pressure in the manufacturing process. Therefore it is necessary to vacuum the cavity and have a vacuum pump to maintain the low-pressure environment, and thus incurring a high cost, a high maintenance fee, and a significant decrease of processing quantity per unit time. For example, the vacuum pump is easily damaged by strong acids, strong alkalis, and microparticles. As a result, it is a major subject for related manufacturers to produce plasma stably under atmospheric pressure by simple equipments, operations and maintenance fees without requiring the use of the aforementioned equipments, such that the device can be operated easily and continuously to increase the processing quantity without being limited by the size of the vacuum cavity.
Since the atmospheric pressure plasma technique does not have the foregoing limitations, this technique involves lower equipment and operation costs and provides a fast operation, and thus, it is applicable for the operations in a continuous manufacturing procedure, and this technique can be used with any combination of other continuous equipments to enhance the production efficiency. Compared with the traditional low-pressure plasma, the atmospheric pressure plasma expands the application of the plasma significantly, particularly the atmospheric plasma jet system has a feature of producing non-thermal plasma and it can be integrated with a manufacturing process in a production line easily and catches much attention of the related manufacturers. Since the plasma jet system has the feature of power saving, easy operation and maintenance, and small volume of the equipment, it has tremendous potential to be applied in the industry.
In related arts and applications, U.S. Pat. Application No. US20060048893 discloses a non-arcing atmospheric pressure processing reactors comprising (a) a wafer platform that is electrically conductive; (b) at least one radio frequency electrode operatively placed near said wafer platform to allow creation of an electric field between said wafer platform and said at least one radio frequency electrode; (c) an RF power supply electrically attached to said at least one radio frequency electrode and said wafer platform to create said electric field for generation of said non-arcing atmospheric pressure plasma; (d) a process gas supplier comprising a mixture of 90% to 99% support gas to 1% to 10% reactive gas to create said non-arcing atmospheric pressure plasma in the presence of said electric field. U.S. Pat. No. 3,585,434 discloses a plasma jet generating apparatus, comprising a cathode formed of an annular electrode and an anode formed of a cylindrical electrode inserted at the central portion of said annular cathode wherein an arc is generated between the electrodes to heat a gas to a high temperature. In addition, U.S. Pat. No. 5,961,772 discloses an atmospheric-pressure plasma jet comprising: (a) an electrically conducting, grounded cylindrical chamber which is not tapered having a closed end, an open end, and a longitudinal axis; (b) a cylindrical electrode located within said cylindrical chamber having a longitudinal axis and disposed such that the longitudinal axis thereof is collinear with the longitudinal axis of said cylindrical chamber, defining thereby an annular region; (c) a cylindrical insulating cap located at the end of said cylindrical electrode at the end thereof closest to the open end of said cylindrical chamber, and inside said cylindrical chamber, for preventing arcing between said cylindrical electrode and said cylindrical chamber.
However, there is still no atmospheric plasma jet system provided for converting carbon dioxide into organic products.
It is noteworthy to point out that the foregoing cited references are provided for describing the background of the present invention, and the contents of these references are well known arts.